Abstract:In order to improve the coordination and unification between the tunnel portal and the natural environment， the color theory and image processing technology are applied to study the color coordination of highway tunnel wall portal with the environment in China. In this paper， by conducting a survey questionnaire and introducing the hue coordination theory， the design criteria for the color coordination of tunnel portals are constructed， that is， the hue conforms to the harmonic coordination type， and the saturation and lightness are both weak contrast types. Based on this criteria， a quantitative design method for tunnel wall portal color is proposed. The cluster analysis is used to extract the color attributes of the tunnel entrance environment image and convert them into the HSV（hue， saturation， value） color space. The hue harmonic type is analyzed， the saturation and lightness are calculated， and the value range of the three attributes of the portal color is determined. A case study of an existing tunnel is conducted using the color design method， and the coordination evaluation results are consistent with the subjective questionnaire results， which verifies the feasibility and effectiveness of the method and provides a scientific basis for the design of new tunnel portals.

Abstract:At present， cement mortar is used as the grouting material for synchronous grouting， and the slurry permeates in the soil during grouting and consolidation， resulting in the decrease of slurry volume. If the subsequent grouting is not timely， it is easy to cause the grouting of shield tail gap not to be dense. The lightweight intelligent synchronous grouting material contains bubbles， because of its compression “elasticity”， with the consolidation and unloading of the slurry， although some of the slurry diffuses， the volume of the slurry remains unchanged in the gap between the tail of the shield， ensuring the density of the synchronous grouting. In this paper， the mapping relationship between density and pressure of the lightweight intelligent synchronous grouting material is studied， and the theoretical model of compression of lightweight intelligent synchronous grouting material is established. The principle of high density grouting of lightweight intelligent synchronous grouting material is qualitatively analyzed. According to the composition characteristics of lightweight intelligent synchronous grouting material， the consolidation and diffusion mechanism of compressible intelligent synchronous grouting material based on percolation effect is established. The results show that the volume of the slurry decreases with the increase of the pressure of the compressible synchronous grouting material. The experimental results show that the variable parameters of the pressure-density curve of the lightweight material have a strong correlation with the bubble content. The formation permeability coefficient has a significant influence on the consolidation diffusion distance of slurry. The larger the formation permeability coefficient is， the more significantly the consolidation diffusion distance of lightweight intelligent synchronous groutingmaterial is affected by the soil mechanical properties.

Abstract:Bearing capacity is one of the most important mechanical properties of the segment lining structure of shield tunnel, whoes accurate evaluation is the key to ensuring the safety of the structure under stress. However, there is currently no mature evaluation method. Based on the stress and deformation characteristics of segment and segmental joint， the evaluation method and index for evaluating the bearing capacity of segment lining structure with the bearing capacity of segment and segmental joint involved were established in this paper， the prototype failure tests of straight-joint assembly structure （STRS） and staggered-joint assembly structure （STGS） were preformed to verify the proposed evaluation method， in combination with the field monitoring tests， the bearing state of the segment lining structure in the actual project is quantitatively evaluated and analyzed. The results show that the failure phenomenon of segmental joint is more obvious in the failure tests of STRS， and the joint reaches its ultimate bearing capacity before the segment， while in the failure tests of STGS， the failure phenomenon of segment is more obvious， and the segment reaches its ultimate bearing capacity before the joint. In the failure tests of STRS and STGS， the failure of segment and segmental joint occur simultaneously with their internal forces reaching the ultimate bearing capacity， indicating that the proposed evaluation method is reasonable. The bearing safety factors of segment and segmental joint in the selected section are 4.27 and 4.86 respectively， indicating that the bearing state of the selected section is good. The research methods and conclusions of this paper can provide important support for bearing safety assessment of similar segment lining structure in shield tunnels.

Abstract:Based on the difference in basic principles of digital image technology， the application status， technical development， and basic principles of two-dimensional digital image measurement methods such as digital image correlation （DIC） and particle image velocimetry （PIV） in tunnel model test are summarized. Moreover， the principle of the three-dimensional measurement method and its application potential in tunnel model tests are analyzed. Furthermore， the application of digital image measurement technology in the tunnel model test is demonstrated through the tunneling simulation test of the shield tunnel in the loess stratum. The results show that DIC， digital photogrammetry for deformation measurement（DPDM）， and other non-contact measurement methods judge the displacement of each point by the correlation of points on the photo， and the use scenarios are more inclined to the deformation monitoring of civil structures such as indoor test roads， bridges， tunnels， foundations， dams， steel structures， and steel-concrete structures. PIV analysis can measure the size and direction of the fluid flow and is widely used in the study of fluid motion， such as slurry， debris flow， and fountains. Based on the indoor model test scheme of the shield tunnel in the loess stratum， it is found that the disturbance range of surrounding rock is about 1D on both sides of the central axis of shield tunneling and 1D above the shield when the shield tunneling is eight-ring segment distance in low water content loess stratum.

Abstract:To realize the intelligent prediction of the floating process of shield segment during construction， the dynamic level was used to automatically monitor the floating process of shield segment， and an intelligent prediction model of segment floating process based on convolutional neural networks and long short-term memory （CNN-LSTM） deep learning algorithm was established. The results show that the floating stage of segment is in a shape of “ladder”， i.e.， the floating of segment mainly occurs during shield tunneling. In addition， the floating amount in the heading state is the largest， accounting for 75.24 % to 98.29 % of the peak value. The mean square error （MSE）， average absolute error （MAE） and determination coefficient R2on the training set are 0.038 7， 0.148 2， and 0.999 3 respectively， and 0.030 7， 0.138 9 and 0.801 9 on the test set. Compared with the back propagation （BP） model， the performance of the CNN-LSTM model in the training set and test set has been improved， and the improvement of the test set is more obvious， up to 89.71 %. The research results can provide a new idea for field measurement， prevention， and treatment of shield segment floating.

Abstract:When the shield tunnel passes through the sandy cobble stratum， it is easy for the tunnel face to lose stability and cause accidents due to the stratum characteristics and construction disturbance of sandy pebble. In order to study the minimum supporting force required for the stability of the shield tunnel face in sandy cobble stratum， in combination with the instability mode of the tunnel face in sandy cobble stratum， and based on the three-dimensional Murayama model， the sliding surface of the soil in front of the tunnel face is assumed to be a logarithmic spiral slip line. In combination with the failure mechanism of the upper loose area， the ellipsoid drawing theory is introduced to improve the traditional prism silo model， and the limit support of the tunnel face in sandy cobble stratum is further derived by using the limit equilibrium method. Finally， the formula is verified by discrete element numerical simulation， and the error between the two is 3.1 %. The results show that the formula can accurately solve the limit support force of the tunnel face in sandy cobble stratum. The research results are expected to provide new ideas for the calculation of limit supporting force of tunnel face in sandy cobble stratum.

Abstract:The inside of a small-radius highway long tunnel is a typical weak visual reference environment， which easily induces the mental rotation effect of drivers. As a result， it becomes difficult to accurately identify the alignment， the contour of the tunnel， and the traffic information， leading to a decrease in driving performance and an increase in driving risks. To alleviate the mental rotation effect of drivers and improve the traffic safety of small-radius highway long tunnels， this paper proposes a visual environment optimization research framework for small-radius highway long tunnels based on the mental rotation effect， starting from typical driving safety issues in its visual environment. The results show that the visual reference system of small-radius highway long tunnels has characteristics such as inducing a significant transition of information， violating driving expectations， and lacking redundancy， which are prominently manifested in aspects such as discontinuous visual guiding information， inconsistent local visual reference information with the overall visual environment information， and poor collaboration between contour and alignment guiding information. Based on evaluation factors such as spatial right-of-way， driving human factors， and driving tasks， and in combination with theories such as visual perceptual constancy， global-precedance， and multi-level guiding， this paper proposes an optimization idea of constructing a constant， stable， continuous， and redundant visual reference system. In summary， this paper proposes to deploy multi-frequency， multi-scale， and multi-shape visual guiding facilities， and use local visual reference elements to construct a continuous and consistent reference clue with the overall driving environment information， enhance contour and alignment guiding， and construct a multi-level visual reference system with redundant information by leveraging the collaborative effect of high， middle， and low-level guiding information to effectively alleviate the negative impact of mental rotation effect and achieve the optimization goals of driving safety， comfort， low cost， and sustainability. This paper can provide a theoretical basis for enhancing traffic safety in small-radius highway long tunnels and small-radius optical long tunnels.

Abstract:In order to determine the difference and similarity of along-wind loads of high-rise buildings between Chinese Taiwan and Chinese mainland areas， benchmarking analysis was used to compare the wind load code for buildings on both sides of the Taiwan strait， and multi-factor analysis of along-wind loads of high-rise buildings was conducted using the uniform design method. The results show that there are significant differences in the basic wind speed sample method and extreme distribution parameter estimation methods. The wind pressure height coefficient distribution and conversion coefficient of design wind speed in different return periods for the two standards are roughly the same； The turbulence intensity values of the Taiwan code is significantly larger than that of the mainland code； For the wind pressure calculation of main wind-force resisting system and cladding， Taiwan wind load code adopts classification method， while the Mainland wind load code adopts a unified expression. There are significant differences between the two standards in the combination of design wind loads of along-wind， cross-wind， and torsional directions. Taking the base shear and base bending moment as evaluation indexes， the influence of aspect ratio H/BL， exposure factor α， gust effect factor C_g， wind load shape coefficient C_p ， and turbulence intensity I_z on the along-wind loads of high-rise buildings gradually decreases， and the aspect ratio and exposure factor are the main influencing factors. The influence of gust effect factor on along-wind load increases with the increase of the aspect ratio of the structure， and when the aspect ratio increases to a certain value， it becomes the main factor that dominates the along-wind loads of the both sides.

Abstract:A continuous profiled steel sheeting-concrete composite bridge deck specimen with perfobond（PBL） connectors was tested to study the mechanical behavior at variable amplitude fatigue load. The specimen is 9.25 m long and 1.5 m wide， the thickness of the profiled steel sheeting is 3 mm， and the depth of concrete is 24 cm. The mid-span deflection， the strain of concrete and reinforcement， and the distribution of cracks and crack widths at the hogging moment region， as well as the procedure of the degeneration of stiffness and the fatigue failure mode were obtained and discussed. The test results show that the mechanical behavior of the composite deck specimen deteriorats with the increase in the fatigue loading times. The specimen does not fail at a fatigue loading of 600×10⁴ times， which shows that the composite deck has a high fatigue strength. The fatigue failure mode of the specimen is the steel sheeting crack at the mid-span， and the fatigue crack initiats at the welding part of the PBL connectors and steel sheeting. Meanwhile， the maximum crack width of concrete at the hogging moment region reaches 0.2 mm at static load. The applicability of the existing S-N curve to the composite deck was analyzed by using the linear damage accumulation rule.

Abstract:To explore the failure process of excavation face and setting of support force during shield tunneling， a three-dimensional engineering discrete element method（EDEM） analysis is conducted for the excavation face failure case in sandy cobble strata of Chengdu Metro. The limit support pressure and excavation face stability are analyzed under the conditions of different support force distributions. Based on the tunneling data observed in the excavation face failure case， the suggested values of two parameters during shield tunneling is proposed for stability of excavation face considering the overall mechanical performance of shield machine. The results show that the failure position of the excavation face is related to the support force distribution. The soil arching effect occurs within 0.75 D above the shield as the excavation face is in the limit state. The failure zone gradually develops to ground surface as the support force decreases to 0.1 P₀. The chamber pressure should be kept less than the static earth pressure with a low rotation speed of cutter head during tunneling， which is supposed to reserve enough cutter head torque for possible large size boulders and chamber pressure control.

Abstract:In-situ soft clays are in K₀ consolidation state and present mechanical nonlinearity and anisotropy， However， in laboratory triaxial shear tests isotropic consolidation is usually adopted. At present， there has been no systematic comparison and summary of the differences in the modulus E_u of undrained shear between K₀ consolidation and isotropic consolidation. Three kinds of triaxial shear tests， isotropic consolidation undrained compression （ICUC）， K₀ consolidation undrained compression （ACUC）， and K₀ consolidation undrained extension （ACUE）， were conducted on undisturbed and remolded specimens of Shanghai soft clay. The stress-strain curves， nonlinearity of the undrained modulus E_u and the parameter values of the hyperbolic model are presented and compared. The results show that at the same strain level， the E_u of the ICUC test is close to that of the ACUE test， but larger than that of the ACUC test； The ACUC test and ACUE test have similar initial modulus and failure ratio. Based on the test results and the hyperbolic model， a unified equation of the normalized modulus for the three kinds of undrained shear tests was developed and the parameter values for Shanghai soft clay were summarized.

Abstract:The on-ramp merging area is the bottleneck of the freeway system， the breakdown of which will trigger many problems such as the deterioration of traffic congestion， traffic oscillation， and increase in accident rate. Currently most studies aim to improve the operation of merging area by adjusting the merging behavior of on-ramp vehicles or controlling the speed of the mainline vehicles. This research， on the other hand， focus more on the potential of mainline vehicles in lifting the traffic throughput by dynamically controlling the upstream lane flow distribution. Specifically， a lane changing advisory optimization model under the connected vehicles （CV） environment is proposed， in which the lane changing decision （change to the left/right lane or keep the current lane） of each individual CV is optimized to reduce the disruption caused by the merging vehicle and thus improve the efficiency. The optimization model is formulated as a mixed integer linear programming，which is independent of the critical density derived from fundamental diagram. Based on traffic simulation software VISSIM， a real-time evaluation platform is developed， in which the proposed lane changing advisory method is implemented and further validated under various traffic demand combinations and CV penetration rate. Trajectories from all the lanes show that this method could effectively reduce the conflict of merging vehicles. The averaged traffic delay analysis results reveal that the proposed method can significantly improve the operation efficiency if the average traffic flow level is near the critical flow of traffic breakdown， i.e.， 1 550 –1 800 veh·h^-1 per lane. In such scenarios， the average traffic delay could be decreased by 10 %–50 %. Furthermore， the sensitivity analysis on CV penetration rate show that at a with lower CV penetration rate of 0.2–0.5， the proposed method is capable of reducing traffic delay.

Abstract:Aimed at the phenomenon that local congestion is easy to evolve into large-scale congestion due to the decentralized coordinated control of the mixed network composed of the expressways and the surface streets， as well as the unbalanced distribution of traffic flow pressure in the road network during peak hours， a centralized cooperative optimization model LC-MPC（level change - model predictive control） of mixed network with changeable game roles between authority and users is constructed based on Stackelberg Games. User compliance rate is taken as the equilibrium index to represent the pressure distribution of road traffic flow， while role-change function is designed to fulfill the transformation of the relationship between leader and follower under different traffic states. The central controller of model predictive control（MPC） realizes the synchronous optimization solution of CAC （combined traffic assignment - signal control problem） of the mixed network. Finally， the effectiveness of the designed model is verified by comparing with different control models. The results show that the LC-MPC model with the highest degree of centralization has a better effect on reducing road network travel cost than other control models. Meanwhile， the model can maintain the user compliance rate within a certain range， which is conducive to the balanced distribution of traffic flow and the overall stability of the road network.

Abstract:The evaluation of ride comfort of railway vehicles related to vibration is mainly based on the standard of ISO 2631-1， UIC 513 and GB/T 5599. Among them， the Sperling index algorithm in the GB/T 5599—2019 specification widely used in China shortens the sampling time from 18–20 s in the 1985 version to 5 s， the same as the UIC513 standard， which results in an increase in the index result from the same test data. The algorithms of the three standards for ride quality or ride comfort were analyzed with the measured data and the simulation data to study the index consistency about the sampling time and the mechanism. Then the frequency resolution was used to quantify the instability of the index results caused by the weighted spectrum with non-square value due to the mismatch of time-frequency energy conversion. Based on this， the corresponding correction algorithm of ride quality consistency is proposed. The results show that the algorithms in the standards ISO 2631-1 and UIC 513 are based on the energy correspondence of time-frequency domain conversion of vibration data， whose ride comfort results are not related to the sampling time length. However， the cube value algorithm in the frequency domain adopted in GB/T 5599 does not meet the energy consistency principle. With the influence of the fence effect and energy leakage， shortening the sampling time increases the amplitude of the acceleration spectrum， which leads to an increase in the ride quality index in turn. The consistency correction algorithm of ride quality index based on the unified frequency resolution proposed in this paper was validated by the dynamic simulation data， providing a theoretical basis for improving the vibration comfort related algorithms and evaluation limits in vehicle dynamics analysis and testing.

Abstract:In the past， the potential sound source area was divided into mounts of grids according to the beamforming algorithm， and all the sound sources were mapped into the grid points， which would lead to an incorrect sound source localization and intensity calculation， and the calculation accuracy and efficiency were affected by the size of grid spacing. In this paper， the multi-layer perceptron neural network and grid-free strategy are used to improve the spatial resolution and computational efficiency of sound source identification. Compared with the conventional cross-spectrum algorithm， with the algorithm of multi-layer perception， the spatial resolution can be improved in the depth direction as a planar array was applied to identify and localize two- point sound sources with the same intensity. In addition， multi-layer perceptron is superior to the conventional cross-spectrum algorithm in positioning error. Meanwhile， the intensity error of sound source identification is reduced. Moreover， multi-layer perceptron is superior to the beamforming algorithm at a low frequency range， which can be used as compensation for the poor spatial resolution of beamforming algorithm at this range.

Abstract:Aimed at the robustness problem caused by the impulsive noise in the road noise active control system， an active control method for the impulsive noise was proposed. First， the road noise acquisition test was conducted， 4 optimal reference signal positions were selected， and the data of road impulsive noise were collected. Then， based on the multi-channel adaptive filtering algorithm， an impulse noise active control algorithm combining the normalized multi-channel adaptive filtering algorithm and the symbolic algorithm was proposed. After that， based on the proposed impact noise active control algorithm， a simulation model of the road noise active control system was built， and the collected impact noise signal and acceleration signal were used for simulation analysis. Finally， using four selected acceleration signals and one loudspeaker to control the road noise at the driver’s place， an active control test of road impact noise was performed to verify the effectiveness of the method proposed. Compared with the original algorithm， the stability and noise reduction effect of the algorithm have been greatly improved.

Abstract:In order to understand the current status of research in the field of electric shared vehicles， the basic concept and development stages of electric shared vehicles were sorted out， the dynamic relocation problem of electric shared vehicles was defined， the influencing factors of fleet dynamic relocation are analyzed from the supply side， the demand side， and the matching side， and the corresponding literature reviews were conducted， including user acceptance and preference， trip demand forecast， real-time electricity consumption estimation and prediction， infrastructure layout and planning， dynamic relocation optimization model， and the dynamic relocation solution algorithm， etc. Finally， research gaps and future research directions were summarized.

Abstract:A superhydrophobic self-cleaning composite coating applied to the surface of a condensing heat exchanger was prepared by adding nano-silica and other materials to polyfluoroalkoxy（PFA）， polytetrafluoroethylene（PTFE） and epoxy resin（EP）. The composite coatings were tested for contact angle， thermal conductivity， wear resistance， bonding strength and self-cleaning properties to study its comprehensive properties. The test results show that the contact angles of the PFA coating containing 7.5 %–9.4 % nano-SiO₂ and the PTFE coating containing 1.4 %–2.3 % nano-SiO₂ are both above 150°， and its surface self-cleaning is excellent. The thermal conductivity of coatings can be increased from 0.2 W·m^-1·K^-1 to more than 2 W·m^-1·K^-1 by adding 0.8 %–1.7 % of graphite. The wear resistance of the coating increases with the increase in the SiC content. For the PFA superhydrophobic coating， the addition of SiC enables the coating to maintain good hydrophobicity after grinding. The bonding strength of the epoxy resin coating reaches ASTM （American Society of Testing Materials)grade 5B， while that of the PFA coating and PTFE coating is 4B and 3B， respectively.